In 229 patients admitted to the coronary care unit (CCU) at Sahlgren's Hospital developing inferior myocardial infarction, and with no previous myocardial infarction, the clinical outcome was related to the presence of ST-segment depression in 16 anterior chest leads. In all, 64% had anterior ST-segment depression. These patients differed from those not having ST depression in several aspects. They had larger infarcts, as assessed by serum enzyme activity and ECG recording. They were more prone to congestive heart failure and required more treatment for this complication. Their intensity and duration of pain during the first 4 days appeared to be more substantial. During a 5-year follow-up, patients with anterior ST depression tended to have a higher mortality. We conclude that among patients with inferior myocardial infarction and no previous infarction, those with anterior ST-segment depression form a subgroup with a more severe clinical course.